Unless otherwise indicated herein, the description provided in this section is not itself prior art to the claims and is not admitted to be prior art by inclusion in this section.
A wireless communication system may include a number of base stations (e.g., cellular base stations, WiFi access points, or the like) that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices (whether or not controlled by a human user), can operate. In turn, each base station may be coupled with network infrastructure, including one or more gateways, routers, and switches, that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or a packet-switched network such as the Internet for instance. With this arrangement, a UE within coverage of a base station may engage in air interface communication with the base station and may thereby communicate via the base station with various remote network entities or with other UEs.
In a typical system, each base station's coverage area may operate on one or more carrier frequencies and may define various channels for carrying control and bearer communications between the base station and UEs in the base station's coverage. Further, the base station may work with UEs in its coverage to manage assignment and/or use of various air interface resources, such as particular channels or portions of channels, for carrying communications to and from the UEs. Using such air interface resources, a UE may engage in various types of communications with remote entities. These communications may include voice communications, such as circuit-switched voice calls or voice over Internet Protocol (VoIP) calls, as well as non-voice communications, such as video streaming, gaming, web browsing, email communication, file transfer, among others.
When a UE engages in voice communication with a remote entity, the UE and the remote entity may make use of an agreed voice codec to facilitate efficient transmission of voice in digital form. Considering a voice call between two users each operating a respective device, for example, each device may receive voice from a user, sample and digitize the voice to produce a representative digital bit stream, apply a voice codec to the bit stream to produce an encoded bit stream, and transmit the encoded bit stream to the other device. The other device may then receive the encoded bit stream, apply the voice codec to the decode the encoded bit stream so as to uncover the digital bit stream, and convert the digital bit stream to analog form for playout to user.
Voice codecs may be fixed rate or variable rate. A fixed rate voice codec represents voice by a fixed number of bits per unit time, such as for every 20 milliseconds of voice. A variable rate codec, on the other hand, may have a range of encoding rates for representing voice with a varying number of bits per unit time. Examples of variable rate voice codecs include, without limitation, Adaptive-Multi-Rate Narrowband (AMR-NB), Adaptive-Multi-Rate Wideband (AMR-WB), and Enhanced Voice Services (EVS). When using a variable rate codec, a device engaged in a voice communication may determine that the voice codec rate should be changed to a particular rate and may inform the other device, and the communication may proceed using the new codec rate.
In a wireless communication system, the voice codec rate used by a UE could be set dynamically based on the strength or quality of the UE's air interface communication with a base station. For instance, if the UE is in weak coverage of the base station, the UE could use a lower voice codec rate to help increase the chances of successful communication over the weak air interface. Whereas, if the UE is in strong coverage of the base station, the UE could use a higher voice codec rate to help improve quality of the voice communication.